Rubber auxiliary CBS production wastewater is characterized by high concentration of organic matter and poor biochemistry. A project design adopts the combined process of iron-carbon microelectrolysis_Fenton oxidation-ABR anaerobic-A/0-coagulation and precipitation-filtration, which introduces the process flow, design and operating parameters.

Project Overview
Rubber auxiliary CBS is a kind of vulcanization accelerator, which is often produced by the reaction between accelerator 2-mercaptobenzothiazole (hereinafter referred to as M) and cyclohexylamine as raw materials under the action of oxidant in large-scale production, and the wastewater from the production of CBS is generally characterized by high salinity, high COD content, and poor biochemistry, which leads to the high cost of wastewater treatment, and the pressure of wastewater treatment is larger in the enterprise. Henan a rubber auxiliary production enterprise annual output of 30,000t rubber auxiliary CBS project, the main pollutants in the wastewater are M, benzothiazoles, ring has been amine, resin (raw materials M with people, the vast majority of benzothiazole), sodium chloride, etc., the main pollutants have a complex molecular structure, the pollutant concentration is high, the wastewater has a high salt content, the effect of direct biochemical treatment is poor.

Wastewater treatment process
CBS production wastewater flows into the adjusting tank after pretreatment in the workshop, adjusting the water quantity and water quality, and then entering the iron carbon microelectrolysis tower and Fenton oxidation tank for pretreatment to oxidize the difficult-to-degrade macromolecular organic matter, make it open the ring and break the chain, and decompose it into easy-to-degrade small molecule organic matter to remove part of the COD and improve the biochemistry of wastewater at the same time. After pretreatment, the wastewater enters into ABR anaerobic tank, ABR anaerobic tank is a high-efficiency reactor consisting of several reaction chambers connected in series, the wastewater flows up and down along the folding plate in the reactor, and passes through the sludge bed of each reaction chamber in turn, and the organics in the wastewater are removed by contacting with microorganisms, and the ABR has the excellent performance of good hydraulic conditions, strong biosolids retaining capacity, good distribution of biotic population and simple structure, and fast startup speed. ABR has excellent performance such as good hydraulic conditions, strong biosolids retention capacity, simple structure with good distribution of biological populations, fast start-up speed, etc.

Design features
(1) The wastewater of this project has high concentration of organic matter and poor biochemistry, so the design of pretreatment adopts the iron-carbon microelectrolysis-Fenton oxidation process to significantly reduce COD, BOD5 and other major pollutants while improving the biochemistry of wastewater, which is conducive to enhancing the effect of the subsequent biochemical treatment. (2) In view of the situation of the pretreatment effluent's high concentration of COD and low biochemistry, the design adopts the anaerobic process of ABR, which gives full play to the characteristics of anaerobic biochemistry. The anaerobic biochemical process is designed to give full play to the characteristics of anaerobic biochemical process, to achieve the goals of reducing COD and improving the biochemistry of wastewater at low operating cost, and to reduce the pressure of subsequent aerobic biochemical process. (3) The depth treatment adopts coagulation and sedimentation-filtration process to further remove suspended solids and colloids in wastewater, and to ensure that the effluent meets the second-grade standard of GB 8978-1996, and that the quality of effluent is stable and meets the standard.

Operation effect
After 60d of commissioning, the water quality indicators of each system tend to be stable, in which the iron and carbon microelectrolysis-Fenton oxidation pretreatment system is commissioned for 7d, the pH value of iron and carbon microelectrolysis is 3.0, and the dosage of Fenton oxidizing agent is 24 L/h of hydrogen peroxide and 14.5 kg/h of "Fe²"; ABR anaerobic-A/0 in biochemical section is commissioned for 50d, and the reflux ratio of ABR is controlled to be 50%, and that of A/0 sludge is 100%, and the mixing ratio is 100%, and the quality of mixed water is stable. The reflux ratio of ABR is 100%, and the reflux ratio of mixed liquor is 400%; the coagulation and sedimentation-multi-media filtration deep treatment system is commissioned for 3d, in which the dosage of PAC for coagulation reaction is 40 mg, and the dosage of PAM is 3 mg. 5d consecutively, we take the effluent from the conditioning tank, effluent from Fenton oxidation tank, effluent from the secondary sedimentation tank, and the total drainwater samples at the same time period for analyzing and testing.